Pentagon contractors have spent the last seven years developing a hypersonic successor to the storied SR-71 Blackbird capable of traveling six times the speed of sound for both spying and bombing.

“The jet would fly so fast that adversaries would not be able to react in time to hide a mobile target,” saysAviation Week magazine, which has word of the fledgling SR-72 program in its Nov. 4 issue. Its first flight is still years away.

The plane, under development at Lockheed Martin’s Skunk Works facility in southern California, is designed around partner Aerojet-Rocketdyne’s scramjet engine capable of Mach 6, double the SR-71’s top speed. Bullets generally travel about Mach 2, twice the speed of sound.

“Guided by the U.S. Air Force’s long-term hypersonic road map, the SR-72 is designed to fill what are perceived by defense planners as growing gaps in coverage of fast-reaction intelligence by the plethora of satellites, subsonic manned and unmanned platforms meant to replace the SR-71,” reporter Guy Norris writes. “Potentially dangerous and increasingly mobile threats are emerging in areas of denied or contested airspace, in countries with sophisticated air defenses and detailed knowledge of satellite movements.”

The Pentagon has long been eyeing develop of such a weapon, capable of quickly attacking targets anywhere on the globe, much as the nation’s nuclear missiles can. But crossing the nuclear threshold is a big step that a President would be leery of taking. “A long-range conventional strike capability might enhance deterrence and assurance by providing an effective and usable (and thus more credible) strike option,” a 2011 Center for Strategic and International Studies report said. “For these reasons, a conventional weapon that is faster, travels farther, and is more effective against antiaccess capabilities than existing conventional forces would be a valuable strategic asset.”

Of course, unveiling blueprints and actually building the SR-72 are two different things, especially amid the current defense-budget crunch.